CN109653925B

CN109653925B - Decoupling element for a fuel injection device

Info

Publication number: CN109653925B
Application number: CN201811177401.9A
Authority: CN
Inventors: D·施米德尔; C·海姆格特纳
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-10-10
Filing date: 2018-10-10
Publication date: 2022-09-27
Anticipated expiration: 2038-10-10
Also published as: DE102017218007A1; US20190107092A1; CN109653925A

Abstract

The decoupling element for a fuel injection device according to the invention is characterized in particular by the realization of a low-noise design. The fuel injection device comprises at least one fuel injection valve and a receiving bore in the cylinder head and a decoupling element between a valve housing of the fuel injection valve and a wall of the receiving bore. The decoupling element is embodied in the form of a pot or cup and has a radially outer contact region and a radially inner contact region, by means of which the decoupling element can be brought into contact with the fuel injection valve and a shoulder of the receiving bore radially on the inside and on the outside. The radially inner contact area of the decoupling element has a contact surface corresponding to a convexly curved counter surface on the fuel injection valve. The fuel injection device is particularly suitable for injecting fuel directly into a combustion chamber of a mixture-compressing, spark-ignited internal combustion engine.

Description

Decoupling element for a fuel injection device

Technical Field

The invention relates to a decoupling element for a fuel injection device.

Background

Fig. 1 shows an example of a fuel injection device known from the prior art, in which a flat intermediate element is provided on a fuel injection valve mounted in a receiving bore of a cylinder head of an internal combustion engine. In a known manner, such an intermediate element is placed as a support element in the form of a shim on a shoulder of a receiving hole of the cylinder head. With such an intermediate element, manufacturing and assembly tolerances are compensated for and a support without transverse forces is also ensured even in the case of slightly inclined fuel injection valves. The fuel injection device is particularly suitable for use in fuel injection devices of mixture-compressing, spark-ignited internal combustion engines.

A further simple intermediate element for a fuel injection device is known from DE 10108466 a 1. The intermediate element is a washer with a circular cross section, which is arranged in the following areas: in this region, the walls of the receiving bore in the cylinder head as well as the fuel injection valve run in the shape of a truncated cone, and the washer serves as a compensating element for supporting and supporting the fuel injection valve.

Furthermore, intermediate elements for fuel injection systems that are complex and significantly more complex in production are also known from DE 10027662 a1, DE 10038763 a1 and EP 1223337 a 1. These intermediate elements are distinguished in that they are all of multi-part or multi-layer construction and should partially assume the sealing and damping function. The intermediate element known from DE 10027662 a1 comprises a base body and a carrier body, in which a sealing element is inserted, which is penetrated by a nozzle body of the fuel injection valve. DE 10038763 a1 discloses a multilayered compensating element which consists of two rigid rings and an elastic intermediate ring arranged in a sandwich-like manner between the rigid rings. The compensating element enables both a tilting of the fuel injection valve relative to the axis of the receiving bore over a large angular range and a radial displacement of the fuel injection valve from the center axis of the receiving bore.

An intermediate element of the same multilayer type is also known from EP 1223337 a1, wherein the intermediate element consists of a plurality of shims which consist of a damping material. The damping material made of metal, rubber or PTFE (polytetrafluoroethylene) is selected and designed in such a way that a noise damping of vibrations and noise generated by the operation of the fuel injection valve is possible. However, the intermediate element must comprise four to six layers for this purpose in order to achieve the desired damping effect.

DE 102005057313 a1 also discloses a damping element in the form of a disk for fuel injectors, in particular for injectors for injecting diesel fuel in common rail systems. The damping disk should be inserted between the injection valve and the wall of the receiving bore in the cylinder head in such a way that a structure-borne noise damping is also possible with high pressing forces, so that noise emissions are reduced. The annular damping element bears with an annular surface against a bearing surface of the cylinder head and with a circumferential collar against a conical bearing surface of the injector. However, this integral arrangement has the following disadvantages: the bearing points of the damping element on the cylinder head and on the injector, viewed in the radial direction, lie relatively close to one another, and the damping element is implemented relatively hard due to its installation. This results in that in such an arrangement there is always still a clearly audible noise emission.

Furthermore, to reduce noise emissions, US 6,009,856 a proposes surrounding the fuel injection valve with a sleeve and filling the resulting intermediate space with an elastic, noise-damping substance. However, this noise attenuation is very complex, disadvantageous to assemble and costly.

Disclosure of Invention

The decoupling element for a fuel injection device according to the invention has the following advantages: improved noise reduction is achieved in a very simple structural manner by decoupling or isolation. The decoupling element according to the invention is used for a fuel injection device of a fuel injection system of an internal combustion engine, in particular for injecting fuel directly into a combustion chamber, wherein the fuel injection device comprises at least one fuel injection valve and a receiving bore for the fuel injection valve, and the decoupling element is incorporated between a valve housing of the fuel injection valve and a wall of the receiving hole, wherein the decoupling element is embodied in the form of a pot or cup and has a radially outer contact area and a radially inner contact area, by means of which the decoupling element can be brought into contact with the fuel injection valve and a shoulder of the receiving bore radially inwardly and radially outwardly, the radially inner contact area of the decoupling element has a contact surface corresponding to a convexly curved counter surface on the fuel injection valve or on a shoulder of the receiving bore.

It is particularly advantageous if a cardan bearing is also provided between the fuel injection valve and the decoupling element in the radially outer contact region. In this way, a constant, tolerance-independent lever arm can be ensured between the two radial positions of the contact surfaces of the decoupling element over the entire service life during operation. A further advantage of the assembly according to the invention is that it has very little discrete, defined axial stiffness and no lateral forces of axial support. In addition, advantageously, no sharp edge seats are present on the bearing region of the decoupling element.

In a particularly advantageous manner, the inventive shaping of the decoupling element minimizes tensile and compressive stresses in the decoupling element in the installed state.

Advantageous embodiments and further developments of the fuel injection device are given below.

According to one embodiment of the invention, the convex curved counter surface is formed with a constant spherical radius on the fuel injection valve or on the shoulder of the receiving bore.

According to one embodiment of the invention, the counter surface extends on an imaginary sphere, the center point of which lies approximately on the longitudinal axis of the valve or of the receiving bore of the fuel injection valve.

According to one embodiment of the invention, the mating surface of the convex curvature is embodied completely circumferentially in 360 ° as a spherical sector.

According to one embodiment of the invention, the radially outer contact area of the decoupling element has a spherically arched contact surface, the curvature of which is embodied with a radius that is greater than the contact surface radius of the radially inner contact area.

According to one embodiment of the invention, the receiving bore of the fuel injection valve is formed in the cylinder head and has a shoulder against which the decoupling element bears with its radially inner or radially outer receiving region in a cardanic manner.

The radially inner contact surface of the decoupling element ideally corresponds to a convex curvature of the mating surface, which has a center point approximately at the longitudinal valve axis of the fuel injection valve or at the longitudinal axis of the cylinder head receiving bore, which, in addition, leads to an optimum effect in terms of reducing stresses, decoupling noise and centering the decoupling element.

In an advantageous manner, the decoupling element is configured in a disk-like manner and overall in a pot-like or disc-like manner and is produced as a stamped and bent part or as a turned part.

Depending on the use in a variable-pressure system or in a constant-pressure system, the decoupling element is designed in a particularly advantageous manner with a non-linearly increasing spring characteristic or with a non-linearly decreasing spring characteristic.

Drawings

Embodiments of the invention are shown simplified in the drawings and are explained in detail in the following description. The figures show:

figure 1 shows a partially illustrated fuel injection device with a disk-shaped intermediate element in a known embodiment,

figure 2 shows in a cross-sectional view a fuel injection device with a first decoupling element according to the invention,

figure 3 shows an enlarged detail III of figure 2 with a decoupling element in a first installation situation between the fuel injection valve and the cylinder head,

FIG. 4 shows a sectional illustration of a single side of the decoupling element according to FIG. 3 for the visual illustration of the profiling of the decoupling element, an

Fig. 5 shows the valve housing of the fuel injection valve shown in fig. 2 as a single component, wherein the component in the form of a nozzle body or a valve seat carrier is only part of the entire valve housing; and

fig. 6 shows a second embodiment of the decoupling element according to the invention and an enlarged detail similar to fig. 3 in the installed condition between the fuel injection valve and the cylinder head.

Detailed Description

A known embodiment of a fuel injection device is explained in detail below with reference to fig. 1. Fig. 1 shows a valve in the form of an injection valve 1 of a fuel injection system for a mixture-compressing, spark-ignited internal combustion engine in a side view as an exemplary embodiment. The fuel injection valve 1 is part of a fuel injection device. The fuel injection valve 1 is mounted with its downstream end into a receiving bore 20 of the cylinder head 9, and is embodied in the form of a direct injection valve for injecting fuel directly into a combustion chamber 25 of an internal combustion engine. In particular by

The sealing ring 2 formed ensures an optimal sealing of the fuel injection valve 1 with respect to the wall of the receiving bore 20 of the cylinder head 9.

A flat intermediate element 24, which is embodied in the form of a spacer, is inserted between a shoulder 21 (not shown) of the valve housing 22 or a lower end side 21 (fig. 1) of the support element 19 and a shoulder 23 of the receiving bore 20, which extends, for example, at right angles to the longitudinal extent of the receiving bore 20. With such an intermediate element 24 or together with a rigid support element 19 (which has a curved contact surface, for example, inward toward the fuel injection valve 1), manufacturing and assembly tolerances are compensated for and a support without transverse forces is ensured even with a slightly inclined fuel injection valve 1.

The fuel injection valve 1 has, at its inflow-side end 3, a plug connection to a fuel distributor line (fuel rail) 4, which is sealed by a sealing ring 5 between an attachment pipe 6 of the fuel distributor line 4 (which is shown in cross section) and an inflow nipple 7 of the fuel injection valve 1. The fuel injection valve 1 is inserted into a receiving opening 12 of the attachment pipe 6 of the fuel distributor line 4. The attachment pipe 6 here protrudes, for example, in one piece from the actual fuel distributor line 4 and has, upstream of the receiving opening 12, a through-flow opening 15 of smaller diameter, via which the flow to the fuel injection valve 1 is achieved. The fuel injection valve 1 has an electrical plug 8 for electrically contacting the fuel injection valve 1.

In order to keep the fuel injection valve 1 and the fuel distributor line 4 largely spaced apart from one another without radial forces and to press the fuel injection valve 1 reliably in the receiving bore of the cylinder head, a pressing device 10 is provided between the fuel injection valve 1 and the attachment pipe 6. The holding-down device 10 is embodied as an arcuate component, for example as a stamped and bent part. The holding-down device 10 has a partially annular base element 11, from which a holding-down clip 13 extends in a bent-out manner, which in the installed state rests against a downstream end face 14 of the attachment tube 6 on the fuel distributor line 4.

The object of the present invention is to achieve an improved noise reduction in a simple manner with respect to known intermediate element and damper disk solutions, above all in the case of noisy idling operation, but also in constant-pressure systems at system pressure, by means of a targeted design and geometry of the intermediate element 24. In the case of direct high-pressure injection, a decisive noise source of the fuel injection valve 1 is the forces (structure-borne noise) introduced into the cylinder head 9 during valve operation, which result in a structural excitation of the cylinder head 9 and are radiated by the cylinder head as airborne sound. Therefore, in order to achieve noise improvement, efforts are made to minimize the forces introduced into the cylinder head 9. In addition to reducing the forces resulting from the injection, this can also be achieved by influencing the transmission characteristics between the fuel injection valve 1 and the cylinder head 9.

Furthermore, decoupling element 240 should provide its full functionality as stress-free as possible under practical installation conditions. Therefore, the configuration and installation condition of decoupling element 240 between fuel injection valve 1 and cylinder head 9, which minimizes tensile and compressive stresses in decoupling element 240, is selected according to the present invention.

According to the invention, decoupling element 240 is characterized in that it serves to reduce the force flow between fuel injection valve 1 and its installation environment with the aim of reducing unwanted noise excitations in the surrounding structure. In the embodiments of decoupling element 240 described below, the geometric configuration and the material selection of decoupling element 240 take into account the advantageous design of the spring characteristics in each case.

Fig. 2 shows a cross-sectional illustration of a fuel injection device having a first decoupling element 240 according to the invention, while fig. 3 shows an enlarged detail III of fig. 2 of decoupling element 240 in a first installation situation between fuel injection valve 1 and cylinder head 9. This embodiment of the fuel injection system relates to a system for direct gasoline injection with a fuel injection valve 1 which, as shown, is operated as an electromagnetic actuator, but also as a piezoelectric actuator and is used, for example, in a constant-pressure system. Decoupling element 240 is advantageously embodied as a metal perforated disk, which extends in an annular manner in this respect. In this regard, the metallic material is also suitable for being able to be worked in a cost-effective manufacturing method (e.g., turning, deep drawing) in order to be able to dimensionally stably manufacture the desired geometry of decoupling element 240. Decoupling element 240 is particularly suitable for manufacturing as a stamped bent piece. Possible materials for decoupling element 240 are, for example, austenitic stainless steel 1.4310(X10CrNi18-8), which can be deformed very well.

In the installed state, decoupling element 240 has two receiving or contact areas 30, 31: a radially outer abutment region 30 and a radially inner abutment region 31. In the first exemplary embodiment, decoupling element 240 is seated with an outer contact region 30 on a shoulder 23 of receiving bore 20 in cylinder head 9, which shoulder extends, for example, perpendicularly to the longitudinal valve axis. Decoupling element 240 is supported in an annular manner by means of an inner contact region 31 on valve housing 22 of fuel injection valve 1. For this purpose, the valve housing 22 has a conically tapering, beveled housing section 27 which follows the course of the decoupling element 240 radially inward in a certain manner. Thereby simplifying assembly of decoupling element 240.

According to the invention, decoupling element 240 is characterized in that a radially inner contact surface 31 of decoupling element 240 has a contact surface 35, which corresponds to a convexly curved counter surface 37 on fuel injection valve 1. The conically running, beveled housing section 27 of the valve housing 22 ends radially inward in a penetrating manner and then merges directly from this region into the curved counter surface 37. In this case, the convexly curved counter surface 37 on the fuel injection valve 1 is advantageously formed with a constant spherical radius. The mating surface 37 extends on an imaginary sphere, the center point of which ideally lies approximately on the valve longitudinal axis of the fuel injection valve 1. In other words, a spherical sector of the valve housing 22 is annularly expanded by 360 ° completely around a spherical center point, which is located approximately on the valve longitudinal axis of the fuel injector 1, by the spherically arched counter surface 37 at the radially inner contact area 31.

The contact surface 35 in the radially inner contact area 31 of the decoupling element 240 can be designed with a relatively sharp edge, which has the disadvantage of increasing the compressive stress in the decoupling element 240. It is therefore expedient to round the contact surface 35 as well, in particular to round the contact surface 35 with a very small radius, so that a line-shaped contact of the decoupling element 240 on the counter surface 37 of the valve housing 22 is approximately produced. The seating angle beta of abutment surface 35 of decoupling element 240 relative to mating surface 37 is about 45 deg. +/-25 deg..

Generally, decoupling element 240 has a bowl or disk-shaped configuration. With this configuration, typically only a small installation space in the receiving bore 20 of the cylinder head 9 is likewise advantageously used optimally for a constant lever arm which is as advantageous as possible. The likewise spherically arched contact surface 36 in the radially outer receiving region 30 of the decoupling element 240 is either rounded with a constant radius or is also formed with an inconstant radius bulge, a spherical bulge or a convex bulge. In this case, the radius of the contact surface 36 of the radially outer contact region 30 can be selected to be significantly larger than the radius of the spherical counter surface 37 of the valve housing 22, which in turn has a much larger radius than the radius of the contact surface 35 in the radially inner contact region 31, so that tensile stresses which determine the fatigue strength can be reduced in the outer region of the decoupling element 240.

In order to prevent decoupling element 240 on fuel injection valve 1 from being lost before assembly, a securing disk 39, which engages in a press-fit or material-locking manner on valve housing 22, can be arranged below decoupling element 240.

Fig. 4 shows a single-sided sectional representation of decoupling element 240 according to fig. 3 in a further enlarged view for the visual illustration of the contouring of decoupling element 240. In this case, it is clear that the radius of the rounded, radially outer abutment surface 36 is much greater than the radius of the radially inner abutment surface 35, which ultimately engages on the axis, which is rounded in itself and faces the radially inner diameter of the decoupling element 240.

In a simple manner, the inner and outer end faces 41, 42 of the decoupling element 240 extend parallel to the valve longitudinal axis; however, in order to reduce the stresses in decoupling element 240, the inner end face and the outer end face may also extend at a small angle relative to the perpendicular valve longitudinal axis of fuel injection valve 1.

In fig. 5, the valve housing 22 of the fuel injection valve 1 is shown as a single component, wherein this component in the form of a nozzle body or a valve seat carrier is only a part of the entire valve housing 22. It is apparent from the drawing that, in particular, the counter surface 37, which serves as an abutment surface for the decoupling element 240, is embodied convexly curved or spherically, wherein, in the ideal case, as shown, the center point of an imaginary sphere having a radius R (on which the counter surface 37 extends) lies on the valve longitudinal axis of the fuel injection valve 1.

Fig. 6 shows a second embodiment of the decoupling element according to the invention and an enlarged detail similar to fig. 3 in the installed condition between the fuel injection valve 1 and the cylinder head 9. In principle, decoupling element 240 is situated axially reversed in the installed state compared to the previously described solutions. In the installed state, the decoupling element 241 again has two receiving or contact areas 30, 31: a radially outer abutment region 30 and a radially inner abutment region 31. In the second exemplary embodiment, decoupling element 240 now rests with outer contact region 30, for example, on a housing wall 45 of fuel injection valve 1, which extends perpendicularly to the longitudinal valve axis. Decoupling element 240 is supported in an annular manner with an inner contact region 31 on shoulder 23 of receiving bore 20 in cylinder head 9. However, shoulder 23 of receiving bore 20 now has a convexly curved mating surface 47.

According to the invention, decoupling element 240 is again characterized in that: the radially inner contact surface 31 of the decoupling element 240 has a contact surface 35 which corresponds to the convexly curved counter surface 47 on the cylinder head 9. A specially shaped, convexly curved counter surface 47 engages directly radially inwardly as part of the shoulder 23 on a planar shoulder 23 extending at right angles to the valve longitudinal axis of the fuel injection valve 1. In this case, the convexly curved counter surface 47 is advantageously formed with a constant spherical radius on the cylinder head 9. The counter surface 47 extends on an imaginary sphere whose center point ideally lies approximately on the valve longitudinal axis of the fuel injection valve 1 or on the longitudinal axis of the receiving bore 20. In other words, a spherical sector of the cylinder head 9 is annularly expanded by 360 ° completely around a spherical center point, which is located approximately on the valve longitudinal axis of the fuel injection valve 1, by the spherically arched counter surface 47 at the radially inner contact area 31.

The previous explanations regarding the radii and angles also apply to the second embodiment.

Due to the double cardanic bearing of decoupling element 240, a constant, tolerance-independent lever arm can be ensured during operation over the entire service life between the two radial positions of contact surfaces 35 and 36 of decoupling element 240.

Claims

1. A decoupling element for a fuel injection device of a fuel injection system of an internal combustion engine, wherein the fuel injection device comprises at least one fuel injection valve (1) and a receiving bore (20) for the fuel injection valve (1), and the decoupling element (240) is inserted between a valve housing (22) of the fuel injection valve (1) and a wall of the receiving bore (20), wherein,

the decoupling element (240) is embodied in the form of a pot or cup and has a radially outer contact region (30) and a radially inner contact region (31), by means of which the decoupling element (240) can be brought into contact with the fuel injection valve (1) and with a shoulder (23) of the receiving bore (20) radially inwardly and radially outwardly,

it is characterized in that the preparation method is characterized in that,

the radially inner contact area (31) of the decoupling element (240) has a contact surface (35) corresponding to a convexly curved mating surface (37,47) on the fuel injection valve (1) or on the shoulder (23) of the receiving bore (20), wherein the radially outer contact area (30) of the decoupling element (240) has a spherically curved contact surface (36), the curvature of which is embodied with a radius that is greater than the radius of the contact surface (35) of the radially inner contact area (31).

2. The decoupling element of claim 1,

it is characterized in that the preparation method is characterized in that,

the convexly curved mating surfaces (37,47) are formed with a constant spherical radius on the fuel injection valve (1) or on a shoulder (23) of the receiving bore (20).

3. The decoupling element of claim 2,

it is characterized in that the preparation method is characterized in that,

the counter surface (37,47) extends on an imaginary sphere, the center point of which lies on the valve longitudinal axis of the fuel injection valve (1) or on the longitudinal axis of the receiving bore (20).

4. Decoupling element according to one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the convex-arched counter surfaces (37,47) are embodied as a spherical sector completely encircling over 360 °.

5. Decoupling element according to one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the lever arm between two radial positions of the contact surfaces (35,36) of the decoupling element (240) remains constant during operation.

6. Decoupling element according to one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the decoupling element (240) is configured in a ring-disk shape and overall in a pot-shaped or disk-shaped manner.

7. Decoupling element according to one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the decoupling element (240) can be produced as a stamped and bent part or as a turned part.

8. Decoupling element according to one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

a receiving bore (20) for the fuel injection valve (1) is formed in the cylinder head (9), and the receiving bore (20) has a shoulder (23) on which the decoupling element (240) bears with a joint-like support with its radially inner contact area (31) or an outer contact area (30).

9. The decoupling element of claim 1,

it is characterized in that the preparation method is characterized in that,

the fuel injection device is arranged for injecting fuel directly into the combustion chamber.